I recently started working full time (40 hrs/wk) and now have to do my a.m. runs at 5:30. I don't get out for my afternoon workout until 4:45 pm. Consequently, during the week I can only workout in the dark (the joys of living in the great north). It's not a big deal at the moment since my mileage is still low as I recover from Chicago, but soon I will be back up around 120-140. I have pretty much resolved that once the snow flies I will have to run at least my morning run on the treadmill, and maybe some days both runs.
What are peoples opinions on treadmill vs. land running? I've heard some say set it at 2% to compensate for wind/terrain and some say 3%. Is there any real disadvantage to doing the majority of a weeks mileage on the treadmill(besides major brain fade)?